Various proposals have been made for a walking assistance device that is adapted to mount an actuator to the hip joint or knee joint of a person having a walking impediment due to injury, disease or weakened muscle resulting from aging, so that the power from the actuator can be used to assist the movement of the lower limb.
Conventionally, in such a walking assistance device, a rotational force generated by an actuator secured on a support member fastened on the hip portion is transmitted to a support member fastened on the thigh to swing the thigh forward or backward around the hip joint to thereby provide the lower limb with a movement for stepping forward or backward.
However, in the prior art devices, such as those disclosed in Japanese Patent Application Laid-Open Publication No. 58-163364 (FIGS. 1-4) or Japanese Patent Application Laid-Open Publication No. 7-163607 (FIG. 1), when the drive torque from the actuator is applied to the thigh, the force applied to the thigh and hence the load upon the body tends to become undesirably large because a sufficient distance between the torque center and the point of application of force cannot be obtained. Further, because there is a big muscle in the thigh, the support member worn on the thigh tends to move easily even if the support member is fastened with quite a large tightening force, and this can lower the efficiency of transmission of force generated by the actuator.